The present invention relates generally to ammunition storage and more particularly to a volumetrically efficient drum-type ammunition magazine amenable for installation on transport vehicles having a turret type gun.
It is to be appreciated that although the present invention has particular advantage for use in limited space and weight environments, such as aboard transport vehicles, ships and the like, the general principles taught by the invention may have use in other ammunition handling systems.
As to limited space/weight applications, it is desirable that an ammunition magazine be volumetrically efficient, that is, hold a large number of rounds per unit volume. A linkless feed system is desirable in this regard, because linked ammunition necessarily includes the "dead" weight associated with the links which support and help guide the individual ammunition rounds.
In addition, the rate of fire of modern guns may be hundreds or thousands of rounds per minute. This results in very high acceleration and deceleration in the ammunition supply system which make belts formed by cartridge carrying links unsatisfactory because of breakage or separation which may occur.
Further, modern larger caliber guns, such as 25mm, are capable of firing a variety of ammunition types such as high explosive, armour piercing, among others; hence, an ammunition magazine compatable with the weapon for utilizing this feature to its greatest advantage should be able to store more than one type of ammunition and be capable of feeding each type of ammunition to the weapon upon demand without significant interruption of the weapon firing rate.
It is also important that the ammunition magazine be structurally compatable with the turret mounted weapon so that the magazine does not interfere with the range of motion of the turret or otherwise limit the firing envelope of the weapon. In many cases this requires the ammunition magazine to be installed in a remote position from the gun.
Numerous other ammunition magazines that have a general DRUM-TYPE configuration have been invented in the past, and at least three types are known to be in current use. However, none are known that have the ability to independently feed two of more different types of ammunition.
One known type consists of a fixed continuous helical outer partition to guide and support the ammunition case, and a rotating "stave" inner drive means to drive the ammunition rounds, by interface with the projectile and shoulder position of the round, around the fixed helical outer portion. It is easily appreciated that such a continuous outer helical guide is both difficult and expensive to manufacture. Also, because the outer helical guide must be continuous, the inner stave guide means must stop well short of extending radially outward to the base of the round, which results in unfavorable efficiencies and subsequent higher loads and power requirements.
A second type consists of a rotating helical inner drive means (looking very much like a post-hole digging auger) which propells ammunition rounds axially, with the ammunition rounds being restrained and guided by fixed longitudinal tracks in the stationary outer drum. The apparent advantage of this type is that the multiple rows all progress very slowly toward the exit end of the drum. As the ammunition rounds move slowly, the inertia of the ammunition rounds is small which promotes the ability of the system to start very rapidly. Unfortunately, the speed and mass of the rotating center helix is quite large, which detracts from the apparent advantage obtained from low ammunition round velocity, and transmission of drive power to the ammunition round is poor due to high sliding velocities between the rotating center helix and the ammunition rounds. Further, the system is complicated because the ammunition rounds exits the drum at all radial positions, which requires an additional "Scoop Disc Assembly", or the like, to obtain a continuous single stream output at a fixed location. See U.S. Pat. No. 2,935,914, issued to B. Darsie ET AL.
A third type, which is in fact a variant of the second type, utilizes a fixed inner helix with a rotatable outer drum and longitudinal track assembly. This design eliminates the need of a Scoop Disc Assembly, but results in high round inertia.
The present invention provides a lightweight volumetric efficient ammunition magazine capable of storing a plurality of different types of ammunition within a single magazine and separately delivering such different types of ammunition upon demand without the need for expensive helical guides or drive means.